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The time of dusk is the moment at the very end of astronomical twilight, just before the minimum brightness of the night sky sets in, or may be thought of as the darkest part of evening twilight. [4] However, technically, the three stages of dusk are as follows: At civil dusk, the center of the Sun's disc goes 6° below the horizon in the ...
Twilight occurs according to the solar elevation angle θ s, which is the position of the geometric center of the Sun relative to the horizon. There are three established and widely accepted subcategories of twilight: civil twilight (nearest the horizon), nautical twilight, and astronomical twilight (farthest from the horizon).
Blue hour at the Old Cathedral of the Holy Name of Jesus, Bragança in Portugal. The blue hour (from French l'heure bleue; [1] [a] pronounced [lœʁ blø]) is the period of twilight (in the morning or evening, around the nautical stage) when the Sun is at a significant depth below the horizon.
Crepuscular rays usually appear orange because the path through the atmosphere at dawn and dusk passes through up to 40 times as much air as rays from a high Sun at noon. Particles in the air scatter short-wavelength light (blue and green) through Rayleigh scattering much more strongly than longer-wavelength yellow and red light.
Finally, night occurs when the Sun reaches 18 degrees below the horizon and no longer illuminates the sky. [4] Locations further north than the Arctic Circle and further south than the Antarctic Circle experience no full sunset or sunrise on at least one day of the year, when the polar day or the polar night persists continuously for 24 hours ...
Daylight saving time (DST) is the practice of advancing clocks during warmer months so that darkness falls later each day according to the clock.. Proponents of DST generally argue that it saves energy, promotes outdoor leisure activity in the evening (in summer), and therefore is good for physical and psychological health, reduces traffic accidents, reduces crime or is good for business.
Talk: Dusk or Dark or Dawn or Day. Add languages. Page contents not supported in other languages. ... Download as PDF; Printable version This ...
For a location closer to the Equator, the same altitude is reached in less than an hour, and for a location farther from the equator, the altitude is reached in more than one hour. For a location sufficiently far from the equator, the sun may not reach an altitude of 10°, and the golden hour lasts for the entire day in certain seasons.